THE ENTIRE SKULL 



503 



cavity is, approximately, the dis- 

 tance along the middle line, from 

 the opisthion to the point where 

 the posterior edge of the cribri- 

 form plate joins the anterior edge 

 of the anterior sphenoid. 



This diameter does not in- 

 clude the basal length of the 

 small olfactory fossa ; if it is 

 desired to add this, the maxi- 

 mum long diameter of the cranial 

 cavity is taken from the opisthion 

 to the most anterior point of the 

 cribriform plate, which is the point 

 of its greatest convexity forward. 



FIG. 407. 



FIG. 406. 



THE SKULL, EIGHTY DAYS AFTER BIRTH. 



(Natural size.) 



THE SKULL, SEVENTY DAYS AFTER BIRTH. 

 (Natural size.) 



It will be observed that the 

 distance from this point to the 

 posterior edge of the cribriform 

 plate varies in the different skulls, 

 owing to variations in the slope 

 and convexity of the plate itself. 



The maximum basal length of 

 the nasal cavity is the distance 

 from the alveolar point to the 

 anterior edge of the intracranial 

 surface of the anterior sphenoid. 



The oblique long diameter of 

 the nasal cavity is the distance 

 from the alveolar point to the 

 point on the anterior convexity 

 of the cribriform plate. 



